Abnormal aggregation of amyloid proteins,
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. amyloid β (Aβ), Tau and α-synuclein (α-syn), is closely associated with a variety of neurodegenerative diseases such as Alzheimer's disease (AD) and ...Parkinson's disease (PD). Cellular and animal models are useful to explore the neuropathology of amyloid aggregates in disease initiation and progression. In this protocol, we describe detailed procedures for how to establish neuronal and PD mouse models to evaluate amyloid pathologies including self-propagation, cell-to-cell transmission, neurotoxicity, and impact on mouse motor and cognitive functions. We use α-syn, a key pathogenic protein in PD, as an example to demonstrate the application of the protocol, while it can be used to investigate the pathologies of other amyloid proteins as well. The established disease models are also useful to assess the activities of drug candidates for therapeutics of neurodegenerative diseases.
Amyloid aggregation of phosphorylated Tau (pTau) into neurofibrillary tangles is closely associated with Alzheimer’s disease (AD). Several molecular chaperones have been reported to bind Tau and ...impede its pathological aggregation. Recent findings of elevated levels of Hsp27 in the brains of patients with AD suggested its important role in pTau pathology. However, the molecular mechanism of Hsp27 in pTau aggregation remains poorly understood. Here, we show that Hsp27 partially co-localizes with pTau tangles in the brains of patients with AD. Notably, phosphorylation of Tau by microtubule affinity regulating kinase 2 (MARK2), dramatically enhances the binding affinity of Hsp27 to Tau. Moreover, Hsp27 efficiently prevents pTau fibrillation in vitro and mitigates neuropathology of pTau aggregation in a
Drosophila
tauopathy model. Further mechanistic study reveals that Hsp27 employs its N-terminal domain to directly interact with multiple phosphorylation sites of pTau for specific binding. Our work provides the structural basis for the specific recognition of Hsp27 to pathogenic pTau, and highlights the important role of Hsp27 in preventing abnormal aggregation and pathology of pTau in AD.
Protein amyloid fibrillation, a process of liquid to solid phase transition, is involved in the pathogenesis of a variety of human diseases. Several amyloid proteins including α-synuclein (α-syn), ...Tau, amyloid β (Aβ) protein, and TAR DNA-binding protein 43 kDa (TDP-43) form pathological fibrils and deposit in patient brains of different neurodegenerative diseases (NDs) such as Parkinson's disease (PD), Alzheimer's disease (AD) and Amyotrophic lateral sclerosis (ALS). Preparation and characterization of amyloid fibrils
are essential for studying the molecular mechanism underlying the dynamic amyloid aggregation and its pathogenesis in diseases. In this protocol, we take PD-associated α-syn as an example, and describe amyloid protein purification and fibrillation approaches. We then introduce biochemical and biophysical characterization of amyloid fibrils by Thioflavin-T (ThT) fluorescence kinetics assay, transmission electron microscopy (TEM), atomic force microscopy (AFM) and multiple fibril stability measurement assays. The approaches described here are applicable to different amyloid proteins, and are of importance for further study on the structure determination of amyloid fibrils and their pathological function in cells and animal models.
α-Synuclein forms amyloid fibrils that are critical in the progression of Parkinson's disease and serves as the pathological hallmark of this condition. Different posttranslational modifications have ...been identified at multiple sites of α-synuclein, influencing its conformation, aggregation and function. Here, we investigate how disease-related phosphorylation and O-GlcNAcylation at the same α-synuclein site (S87) affect fibril structure and neuropathology. Using semi-synthesis, we obtained homogenous α-synuclein monomer with site-specific phosphorylation (pS87) and O-GlcNAcylation (gS87) at S87, respectively. Cryo-EM revealed that pS87 and gS87 α-synuclein form two distinct fibril structures. The GlcNAc situated at S87 establishes interactions with K80 and E61, inducing a unique iron-like fold with the GlcNAc molecule on the iron handle. Phosphorylation at the same site prevents a lengthy C-terminal region including residues 73 to 140 from incorporating into the fibril core due to electrostatic repulsion. Instead, the N-terminal half of the fibril (1-72) takes on an arch-like fibril structure. We further show that both pS87 and gS87 α-synuclein fibrils display reduced neurotoxicity and propagation activity compared with unmodified α-synuclein fibrils. Our findings demonstrate that different posttranslational modifications at the same site can produce distinct fibril structures, which emphasizes link between posttranslational modifications and amyloid fibril formation and pathology.
Inorganic fillers are generally used as synergistic agent in waterborne epoxy resin intumescent fire-retardant coating. To enhance the flame retardant properties of the coating, modified hexagonal ...boron nitride (h-BN) was introduced. Firstly, the h-BN nanosheets were modified with polydopamine (PDA) through the strong π-π non-covalent interaction between the hexagonal structure of boron nitride and aromatic dopamine molecules. Then, the Ti-O compounds was formed on the surface of the hybrids by covalent modification, which can generate titanium dioxide (TiO2) and titanium pyrophosphate (TiP2O7) at high temperature to enhance the strength of the char layer. The enhancement of the synthetic material (BPT) was evaluated by fire performance measurements and thermogravimetric analysis (TGA). The structure and morphology of the char layer after the fire test were analyzed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) techniques. The results showed that the introduction of BPT hybrids effectively enhanced the strength and oxidation resistance of the char layer and improved the barrier effect to heat and oxygen. Compared with EP, the back temperature of BPT3%/EP steel plate decreased from 259 ℃ to 198 ℃, the expansion ratio increased from 3.04 to 8.91, and the residual char increased from 20.5% to 29.1%.
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•The free radical scavenging effect of PDA can enhance the oxidation resistance.•Grafting of organic titanium onto h-BN@PDA improved coatings' thermal stability.•The introduction of Ti element did not reduce the dispersion of the hybrids.•h-BN@PDA@Ti based IFR coatings exhibited excellent flame retardant performance.
The proper domain size of the active layer plays a key role in determining the exciton dissociation and charge transport in all-polymer solar cells (all-PSCs). However, fine-tuning the domain size ...remains challenging due to low glass transition temperature and negligible mixing entropy in polymer blends. Herein, we systematically studied the influence of “crystallization kinetics” on the domain size and proposed that if the donor and acceptor crystallize simultaneously, they are prone to form a large domain, while if sequential crystallization of the donor and acceptor occurs, a fine phase separation structure with the proper domain size can be obtained. Taking PBDB-T/PNDI blends for instance, the domain size was decreased by using sequential crystallization; meanwhile, the crystallinity and molecular orientation were also optimized, boosting the power conversion efficiency from 6.55% to 7.78%. This work provides a novel way to finely tune the heterojunction phase separation structures.
Firstly, the bio-inspired polydopamine (PDA) was coated on the surface of carbon nitride (CN), then used it (CNP) as nano-dispersant to improve the dispersion of graphene (Gr) in water on the basis ...of π-π interaction. After that, the KH560 was further grafted on the CNPG surface to improve the compatibility between inorganic hybrids and epoxy resin. The results of large plate experiments showed that the backside temperature of composite IFR coating containing CNPG@Si hybrids was significantly lower than that of other samples. Meanwhile, its expansion height after furnace test reached the maximum value (17.8 mm), which was greatly improved compared with the pure epoxy coating. Further, the maximum thermal decomposition temperature and the amount of char residue for the CNPG@Si/EP sample were significantly enhanced through the TGA test result. Besides, CNPG@Si based sample showed the lowest smoke density rating (SDR) due to its excellent smoke suppression performance. From the analysis of the morphology and composition of the char layer for CNPG@Si based sample, it can be seen that the introduction of Gr and CN increased the compactness of the char layer, and silicon network structures remained in the char layer after combustion, which effectively increases its strength and heat insulation effect.
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•CN and Gr were successfully combined by using PDA as an intermediary.•The combination of CN and Gr enhances the thermal barrier effect of coating.•The introduction of PDA improves the antioxidant function of char layer.•Modification of KH560 increases the thermal insulation properties of char layer.
High-performance polymer donors are highly demanded to fulfil the potential of layer-by-layer (LBL) processed organic solar cells (OSCs). In this study, we present an effective method to develop ...high-performance polymer donors for LBL-OSCs by manipulating their solubility properties. The solubility of naphthalenothiophene imide (NTI)-based polymers could be easily manipulated by employing linear or branched alkyl chains in NTI. The polymer PNTB6-Cl with linear alkyl chains insoluble in chloroform could tolerate the chloroform processing by washing away the polymers only in the amorphous region, resulting in an LBL film with a much smoother surface and more efficient photoluminescence quenching, while chloroform-soluble polymer PNTB-Cl did not. PNTB6-Cl:N3 based LBL devices exhibited an efficiency of 17.59%, much higher than 15.24% for PNTB-Cl:N3 based devices and 16.20% for control devices based on PM6:N3. Importantly, the excellent batch-to-batch reproducibility of PNTB6-Cl overcomes the notorious batch-dependent issue in polymer donors, indicating that PNTB6-Cl is a promising polymer donor for LBL-OSCs. Our studies demonstrate that the solubility property of a polymer could significantly impact electron acceptor penetration, phase separation and photovoltaic performance of LBL-OSCs, which provide the guidelines for high-performance polymer donor design.
This study demonstrates that the solubility properties of polymer donors are vitally important for layer-by-layer processed organic solar cells. Manipulating the solubility of an NTI-based polymer donor enables 17.59% efficiency for a PNTB6-Cl:N3 based device.
Microglia-mediated neuroinflammation and α-synuclein (α-syn) aggregation, both as pathological hallmarks of Parkinson’s disease (PD), crosstalk to exacerbate degeneration of dopaminergic neurons and ...PD progression. However, the mechanism underlying their interaction is poorly understood, which obstructs effective therapeutic inhibition of α-syn-induced neuroinflammation. Here, we initiate from structure-based interaction predictions and find that receptor for advanced glycation end products (RAGE) serves as a receptor of α-syn fibrils on microglia. Results of nuclear magnetic resonance (NMR) spectroscopy and mutagenesis validate that the V domain of RAGE that contains an alkaline surface can bind with acidic C-terminal residues of α-syn. Furthermore, the binding of α-syn fibrils with RAGE induces neuroinflammation, which is blocked by both genetic depletion of RAGE and inhibitor FPS-ZM1. Our work shows the important role, as well as the structural mechanism, of RAGE in mediating the inflammatory response of microglia to α-syn fibrils, which may help to establish effective therapeutic strategies to alleviate α-syn-induced neuroinflammation and neuronal damage.
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•α-Syn is a ligand of RAGE receptor•vRAGE uses its positively charged surface to bind with acidic C terminus of α-syn•RAGE mediates the binding of α-syn amyloid fibrils to microglia•Neuroinflammation induced by α-syn fibrils can be mitigated by inhibition of RAGE
Exploring the mechanism underlying the interplay between α-syn and neuroinflammation is important for PD treatment. Long et al. perform a series of biophysical and cellular experiments to demonstrate the structural basis of RAGE-α-syn interaction and the important role of RAGE in PD neuroinflammation. Blockage of the RAGE-α-syn interaction may alleviate α-syn-induced neuroinflammation in PD.
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Cosovlent with different boiling points could play different roles in tuning the crystallinity and domain size of the active layer in polymer/nonfullerene solar cells.
The morphology ...of active layer in bulk heterojunction (BHJ) organic solar cells is decisive to the device performance. Previous works have shown that the solvent engineering is an effective method to optimize the morphology of active layer. However, screening the proper solvent is a tedious task, and we know very little about how to select a proper solvent for a particular system, especially for polymer/non-fullerene blend systems. Here, we combined the spectroscopic analysis in various solvent mixtures during film-forming process to reveal the relationship among the cosolvent characteristics, film-forming kinetics and film morphology. In this article, P3HT/O-IDTBR blend was selected as model system due to being facile synthesized under a large-scale. Chlorobenzene (CB) was selected as main solvent, and the cosolvents were grouped into three categories according to its boiling point (bp) compared to CB. The cosolvents with lower bp, like chloroform (CF), can facilitate a faster film-forming process, reducing the domain size but sacrificing the crystallinity of both components. For the cosolvents with higher bp, like o-dichlorobenzene (DCB) and 1,2,4-trichlorobenzene (TCB), the self-organization process of P3HT and O-IDTBR is separated and its duration was extended, constructing highly crystalline nano-interpenetrating network. However, the cosolvents with very high bp, such as chlornaphthalene (CN), would residue in film and keep P3HT and O-IDTBR self-organizing for longer time, leading to larger phase separation. This work systematically investigated the effect of cosolvent on the film-forming kinetics, and proposed a guideline of how to select a proper cosolvent according to the crystallinity and domain size of active layer.
